In recent years an increasing number of small, noncoding RNAs (sRNAs) have been identified in bacteria. These small RNAs (sRNAs) provide a level of regulation beyond transcriptional control. Often sRNAs inactivate messenger RNAs (mRNAs) by either base-pairing with target mRNA(s) to prevent translation by blocking the ribosome binding site (RBS), or by creating double-stranded RNA molecules that are subject to increased degradation by RNases. However, sRNAs can also act to stimulate the expression of target mRNAs, by binding to structured mRNAs, allowing the release of the RBS. To date, sRNAs have been identified in various species of bacteria, from pound. co//to pathogens such as S. aureus. In addition to regulating a myriad of genes, sRNAs have also been shown to regulate virulence in pathogenic bacteria. The overall goal of this proposal is to identify and characterize sRNAs in mycobacteria, specifically Mycobacterium smegmatis and Mycobacterium tuberculosis. This research could lead to a better understanding of this bacterial family and novel ways to treat tuberculosis. This proposal has two specific aims: 1. Identify sRNAs in M. smegmatis and M. tuberculosis using both traditional laboratory experiments and computational approaches and determine which mycobacterial genomes contain them. 2. Characterize selected sRNA(s) and their regulatory effect. Progress towards the first aim has been achieved through the direct cloning of potential sRNAs from M. smegmatis. These putative sRNAs are being verified experimentally. PUBLIC HEALTH RELEVANCE: Tuberculosis is a re-emerging infectious disease that has become increasingly difficult to treat due to multiple antibiotic resistances. Outbreaks of tuberculosis are becoming more common throughout the globe and novel treatments may be required to once again control this devastating disease. M. tuberculosois may represent another pathogen whose virulence is controlled at least in part by sRNAs. Therefore, basic research on sRNAs in mycobateria will allow us to gain insight into gene regulation in these organisms, an area that has not been well studied to date. This may also lay the groundwork for future studies designed to help combat mycobacterial diseases, such as tuberculosis.